core: Simplify changes to SREG

[simavr] / simavr / sim / sim_avr.h

/*
        sim_avr.h

        Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>

        This file is part of simavr.

        simavr is free software: you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 3 of the License, or
        (at your option) any later version.

        simavr is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License
        along with simavr.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef __SIM_AVR_H__
#define __SIM_AVR_H__

#include <stdint.h>

typedef uint64_t avr_cycle_count_t;
typedef uint16_t        avr_io_addr_t;

struct avr_t;
typedef uint8_t (*avr_io_read_t)(struct avr_t * avr, avr_io_addr_t addr, void * param);
typedef void (*avr_io_write_t)(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, void * param);
typedef avr_cycle_count_t (*avr_cycle_timer_t)(struct avr_t * avr, avr_cycle_count_t when, void * param);

enum {
        // SREG bit indexes
        S_C = 0,S_Z,S_N,S_V,S_S,S_H,S_T,S_I,

        // 16 bits register pairs
        R_XL    = 0x1a, R_XH,R_YL,R_YH,R_ZL,R_ZH,
        // stack pointer
        R_SPL   = 32+0x3d, R_SPH,
        // real SREG
        R_SREG  = 32+0x3f,

        // maximum number of IO registers, on normal AVRs
        MAX_IOs = 256 - 32,     // minus 32 GP registers
};

#define AVR_DATA_TO_IO(v) ((v) - 32)
#define AVR_IO_TO_DATA(v) ((v) + 32)

/*
 * Core states.
 */
enum {
        cpu_Limbo = 0,  // before initialization is finished
        cpu_Stopped,    // all is stopped, timers included

        cpu_Running,    // we're free running

        cpu_Sleeping,   // we're now sleeping until an interrupt

        cpu_Step,               // run ONE instruction, then...
        cpu_StepDone,   // tell gdb it's all OK, and give it registers
};

/*
 * Main AVR instance. Some of these fields are set by the AVR "Core" definition files
 * the rest is runtime data (as little as possible)
 */
typedef struct avr_t {
        const char * mmcu;      // name of the AVR
        // these are filled by sim_core_declare from constants in /usr/lib/avr/include/avr/io*.h
        uint16_t        ramend;         
        uint32_t        flashend;
        uint32_t        e2end;
        uint8_t         vector_size;
        uint8_t         signature[3];
        uint8_t         fuse[4];

        // filled by the ELF data, this allow tracking of invalid jumps
        uint32_t                        codeend;

        int                                     state;          // stopped, running, sleeping
        uint32_t                        frequency;      // frequency we are running at

        // cycles gets incremented when sleeping and when running; it corresponds
        // not only to "cycles that runs" but also "cycles that might have run"
        // like, sleeping.
        avr_cycle_count_t       cycle;          // current cycle
        
        // called at init time
        void (*init)(struct avr_t * avr);
        // called at reset time
        void (*reset)(struct avr_t * avr);

        // Mirror of the SREG register, to facilitate the access to bits
        // in the opcode decoder.
        // This array is re-synthetized back/forth when SREG changes
        uint8_t         sreg[8];
        uint8_t         i_shadow;       // used to detect edges on I flag

        /* 
         * ** current PC **
         * Note that the PC is representing /bytes/ while the AVR value is
         * assumed to be "words". This is in line with what GDB does...
         * this is why you will see >>1 and <<1 in the decoder to handle jumps.
         * It CAN be a little confusing, so concentrate, young grasshopper.
         */
        uint32_t        pc;

        /*
         * callback when specific IO registers are read/written.
         * There is one drawback here, there is in way of knowing what is the
         * "beginning of useful sram" on a core, so there is no way to deduce
         * what is the maximum IO register for a core, and thus, we can't
         * allocate this table dynamically.
         * If you wanted to emulate the BIG AVRs, and XMegas, this would need
         * work.
         */
        struct {
                struct avr_irq_t * irq; // optional, used only if asked for with avr_iomem_getirq()
                struct {
                        void * param;
                        avr_io_read_t c;
                } r;
                struct {
                        void * param;
                        avr_io_write_t c;
                } w;
        } io[MAX_IOs];

        // flash memory (initialized to 0xff, and code loaded into it)
        uint8_t *       flash;
        // this is the general purpose registers, IO registers, and SRAM
        uint8_t *       data;

        // queue of io modules
        struct avr_io_t *io_port;

        // cycle timers are callbacks that will be called when "when" cycle is reached
        // the bitmap allows quick knowledge of whether there is anything to call
        // these timers are one shots, then get cleared if the timer function returns zero,
        // they get reset if the callback function returns a new cycle number
        uint32_t        cycle_timer_map;
        struct {
                avr_cycle_count_t       when;
                avr_cycle_timer_t       timer;
                void * param;
        } cycle_timer[32];

        // interrupt vectors, and their enable/clear registers
        struct avr_int_vector_t * vector[64];
        uint8_t         pending_wait;   // number of cycles to wait for pending
        uint32_t        pending[2];             // pending interrupts

        // DEBUG ONLY -- value ignored if CONFIG_SIMAVR_TRACE = 0
        int             trace;

#if CONFIG_SIMAVR_TRACE
        struct avr_symbol_t ** codeline;

        /* DEBUG ONLY
         * this keeps track of "jumps" ie, call,jmp,ret,reti and so on
         * allows dumping of a meaningful data even if the stack is
         * munched and so on
         */
        #define OLD_PC_SIZE     32
        struct {
                uint32_t pc;
                uint16_t sp;
        } old[OLD_PC_SIZE]; // catches reset..
        int                     old_pci;

#if AVR_STACK_WATCH
        #define STACK_FRAME_SIZE        32
        // this records the call/ret pairs, to try to catch
        // code that munches the stack -under- their own frame
        struct {
                uint32_t        pc;
                uint16_t        sp;             
        } stack_frame[STACK_FRAME_SIZE];
        int                     stack_frame_index;
#endif

        // DEBUG ONLY
        // keeps track of which registers gets touched by instructions
        // reset before each new instructions. Allows meaningful traces
        uint32_t        touched[256 / 32];      // debug
#endif

        // VALUE CHANGE DUMP file (waveforms)
        // this is the VCD file that gets allocated if the 
        // firmware that is loaded explicitly asks for a trace
        // to be generated, and allocates it's own symbols
        // using AVR_MMCU_TAG_VCD_TRACE (see avr_mcu_section.h)
        struct avr_vcd_t * vcd;
        
        // gdb hooking structure. Only present when gdb server is active
        struct avr_gdb_t * gdb;

        // if non-zero, the gdb server will be started when the core
        // crashed even if not activated at startup
        // if zero, the simulator will just exit() in case of a crash
        int             gdb_port;
} avr_t;


// this is a static constructor for each of the AVR devices
typedef struct avr_kind_t {
        const char * names[4];  // name aliases
        avr_t * (*make)();
} avr_kind_t;

// a symbol loaded from the .elf file
typedef struct avr_symbol_t {
        const char * symbol;
        uint32_t        addr;
} avr_symbol_t;

// locate the maker for mcu "name" and allocates a new avr instance
avr_t * avr_make_mcu_by_name(const char *name);
// initializes a new AVR instance. Will call the IO registers init(), and then reset()
int avr_init(avr_t * avr);
// resets the AVR, and the IO modules
void avr_reset(avr_t * avr);
// run one cycle of the AVR, sleep if necessary
int avr_run(avr_t * avr);
// finish any pending operations 
void avr_terminate(avr_t * avr);

// set an IO register to receive commands from the AVR firmware
// it's optional, and uses the ELF tags
void avr_set_command_register(avr_t * avr, avr_io_addr_t addr);
// load code in the "flash"
void avr_loadcode(avr_t * avr, uint8_t * code, uint32_t size, uint32_t address);


/*
 * these are accessors for avr->data but allows watchpoints to be set for gdb
 * IO modules use that to set values to registers, and the AVR core decoder uses
 * that to register "public" read by instructions.
 */
void avr_core_watch_write(avr_t *avr, uint16_t addr, uint8_t v);
uint8_t avr_core_watch_read(avr_t *avr, uint16_t addr);

// called when the core has detected a crash somehow.
// this might activate gdb server
void avr_sadly_crashed(avr_t *avr, uint8_t signal);

#include "sim_io.h"
#include "sim_regbit.h"
#include "sim_interrupts.h"
#include "sim_irq.h"
#include "sim_cycle_timers.h"

#endif /*__SIM_AVR_H__*/